Screw and the method of making same



T. A. OLEARY SCREW AND THE METHOD OF MAKING SAME Dec. '5, 1939.

Filed April 21, 1956 ZSheets-Sheet 1 I Dec. 5, 1939. T. A. O'LEARY 9SCREW AND THE METHOD OF MAKING SAME Filed April 21, 1936 2 Sheets-Sheet2- T; .24 if; 15

- L4 ATTORNEY.

Patented Dec. 5, 1939 UNITED STATES PATENT. oFFIcs Theodor A. Leary,,NewYork, N. Y., assignor of I one-third to Winslow Foster and one-third toHerman Wunderlich, both oi Brooklyn, N. Y.

Application April 21, 1936, Serial No. 75,611 I Claims.

Thisinvention relates to improvements in screws and to the method ofmaking the same and relates more specifically to an improved screw,

' the head of which is provided with an undercut or 5 dovetailed slot.The present improved'screw is particularly adapted to be driven by adriver of the character disclosed in my copending application Serial No.61,931, filed Feb. 1, 1936, the

presentapplication constituting a continuation,

in part of said application.

The improved driver includes a shank having a curved bit portionprovided with fianged edges of such proportions as to more or lessclosely fit the inwardly converging side walls of an arcuate, transverseslot in the screw head of the type disclosed and described in saidapplication. The shank carries a longitudinally movable sleeve, thelower end of which is caused to firmly engage the head of the screwunder the influence of spring pressure or otherwise. Thus the screwisfirmly held in axial alignment with the driver while it is beingdriven, the cooperating flanged bit and undercut slot preventingdisplacement of the screw from the driver. At the finish of the drivingoperation the sleeve is released and the bit portion removed from theslot by moving the handle portion of the driver through an arc.

. The advantages of such a screw and driver are numerous. N0 efiort isrequired to retain the bit in the slot during the driving operation andthe slot can not be damaged, due to the inclination of the driving bitto cut down and into the'screw slot rather than to twist up and out,thereby damaging the head of the screw as well as the surface into whichthe screw is driven. The screw can be driven more quickly than can theconventional screw and with far greater ease, since after the screw isonce well started no pressure against the head is required. v

One of the principal objects of the present invention is the provisionof an improved method for the production of the improved screws at asubstantial reduction in cost over the cost of producing ordinaryscrews. Another object of the invention is to provide a screw having afar stronger head than the conventional screw, the slot beingconstructed in such a manner and shape as topreserve virtually the fullstrength of the head. 3U In the modern manufacture of screws 3. wire iscut to suitable length and thewire supported in a die and the headnormally formed by theupsetting process. In actual practice, one end ofthe wire is first "coned-up" after which this end is forcibly struck bya heading die or punch, the

slot subsequently being cut in with a milling cutter. Efforts have beenmade to form the slot simultaneously with the upsetting of the head, buta punch suitable for performing both the heading and slotting functionat the same instant 6 normally has a short life due to the relativethinness of the male portion in the punch which forms the slot, thismale portion being broken down in a relatively short time. In theimproved screw which constitutes the 10 present invention the finishedslot is wider at the bottom than at the top, and in following thepresent method of screw manufacture the upsetting punch is provided witha transverse male portion of considerable thickness. Thus when the punchstrikes the previously coned-up head portion, a'slot of substantialwidth having parallel side walls is struck in at the same instant as thehead is formed. The more substantial male portion makes for a punchwhich is not easily 20 broken, thereby greatly reducing the cost ofscrew manufacture.

In its presently preferred form the lower wall of the' slot is arcuaterather than straight and when the slot is struck in with the curved maleportion in the punch the metal is caused to flow much more readily thanwould be the case if the slot were straight. After the slot, havingsubstantially parallel side walls and a curved lower wall, is struck inthe head of the screw the head is struck with a second punch or diewhich causes the upper central portion of the side walls to convergeinwardly, thereby providing the desired dovetail 'eflect.

In the drawings:

Fig..1 is a longitudinal, section taken through the preferred form ofdie for use in forming a flat head on a screw in accordance with thepres- "entinvention, the view showingthe previously 40 coned-up wire inposition within the die;

Fig. 2 is a side elevation, partially in section, of .the head-formingand slot-striking punch;

Fig. 3 is also a side elevation of the punch, taken at right angles tothe view shown in Fig. 2;

Fig. 4 is a front elevation of the punch;

Fig. 5 is an elevation, partly in section, of the dleand the fiat punchused for forming the dovetail portion in the head, the view showing thefinished screw head;

Fig. 6 is a plan view of the head of the finished screw; I

Fig. 7 is a side elevation; partially in sectionof the die employed inmaking a round head or button head screw, the view showing a length ofFigs. 8 and 9 are side elevations, partly in section, of the heading andslot striking punches for use in making a round headed screw;

Fig. 10 is a side elevation,'partly in section, of the dovetail formingpunch for use in making round headed screws;

Figs. 11 and 12 are side elevations, partly in section, of the dieandpunch assembly for forming the head and slot in oval headed screws;

Fig. 13 shows the die and punch assembly for dovetailingthe slot in ovalheaded screws;

Figs. 14 and 15 are side elevations, partly in section, of the die andpunch assembly for dovetailing a conventional flat headed screw inaccordance with the present invention;

Fig. 16 is a front elevation of the punch shown in Figs. 14 and 15;

Fig. 1'7 is an exploded view of the die and punch assembly for forming adovetailed slot in a conventional round headed screw in accordance withthe present invention;

Fig. 18 is similar to Fig. 1'?- but shows the die and punch having beenbrought together and the dovetail formed in the slot; and

Fig. 19 is a side elevation of the finished screw mounted on a driver ofthe character described in mycopending application.

The method of making a flat headed screw in accordance with the presentinvention is illustrated in Figs. 1 to 5. A substantially cylindricaldie it is formed with a centrally disposed longitudinal aperture ll,having an outwardly flared die portion l2 corresponding in shape to thelower surfaceof the screw head to be formed. A wire I3 of suitablelength is placed within the longitudinal aperture in the die, the wirefirst having been suitably coned-up as at II. The precise shape of thisconed-up portion is dependentupon the shape and size of the head to besubsequently formed, as will be appreciated by those skilled in the art.The coning-up step is not essential in carrying out the present methodalthough it is desirable since it is a simple operation and re-.

duces the wear upon the heading punch.

The wire I3 is suitably backed up'at l8 and the coned portion is thenforcibly-struck with a combined head and slot forming punch or die IT.This punch is formed with a circular concave area i8 on its forward faceis, the edges of which The outer surface of the male portion is convexlycurved, as will be noted in Fig. 3, the male portion desirablyterminating just short of the periphery of the concave area I8. Thedegree of curvature of this latter area is dependent upon the preciseshape of the finished head. In the case of the flat headed screw,however. it is essential that the curve be not too great in order thatthe dovetailed portion canbe formed to the proper proportions and at thesame time having the screw head of the conventional dimensions or shapeand with the minimum or no excess metal to be shaved.

' is formed with aconcave area 38 provided with what greater thicknessthan the width of the '60 provided with a circular concave portion 6! onits lower face 62, this concave portion having an tens the centralportion of the head of the screw After the punch has struck the conedhead shown in Fig. 1, the head is formed with the arcu ate slotconforming to the male portion 2| of the punch, the lower surface of thehead taking the shape of the tapered portion 1'2 of the die and theupper surface thereof assuming'the curvature of the concave area Ill.The next and final step in themanufacture of the fiat headed screw is tostrike the curved upper surface with the forward face 24 of acylindrical die-25. This blow flattens the head as shown at 26 in Fig 5,and causes the upper central portion of the side walls of the slot 21 toconverge. inwardly. The extreme end portions of the side walls are notconsiderably affected by the blow since they are engaged. by the dieonly at the end of the stroke. Accordingly, the edges 29 of the slot arecurved as shown in Fig. 6 and the slot has its greatest width at itsterminals in order to permit the flanged bit portion of the driver to beintroduced thereinto. In making the round or button head screw the wire32 is coned-up at one end ,in-substantial1y the shape shown at 33, thewire then being placed in the straight longitudinal aperture 34 of thedie 35. In this instance the upsetting punch 31 a greater are than thatformed in the punch i1.

- In this punch the arcuate male portion 39 does not extend beyond theforward face H of the ,to provide the desired dovetail effect and alsogives the head its final shape without materially changing the width ofthe slot at'its terminals.

It is essential, however, that the curved surface of this die does notengage the'fuil length of the edges of the slot, otherwise insertion ofthe bit of the driver into the slot would be diflicult.

In Figs. 11, 12 and 13 there is illustrated the preferred die and punchassembly for forming an oval head on a screw in accordance with thepresent invention. The die 49 is formed with an aperture 50 having anoutwardly flared end portion 5! similar to that employed in making afiatheaded screw. As in the other embodiment, the wire 52 is suitablybacked up at 53. The punch 55 is formed with a circular concave portion56 and with an arcuate slot-striking male portion 51 which protrudesbeyond the lower surface 58 of. the punch. This male portim is also ofsome-i5 conventional slot, 'aashown in Fig. 12. After the punch 55 hasformed the head shown in Figs. 11 and 12, the head is struck with asecond punch arc of a slightly larger circle than the concave portion 56in the punch 55. This punch 80 flatin the manner shown in Fig. 13,thereby forming the dovetailed slot 83. SubstantiaHy the same procedure,with a slightly differently shaped die, may be employed for forming afillister head.

i The herein described method of forming a, dovetailed slot by the useof an upsetting punch may be employed in connection with a conventional.flat headed or round headed screw. In Fig. 14 a die 68 similar to thatshown in Fig. 1 receives a conventional flat headed-screw 69 providedwith a transverse slot 10. The punch II is formed with 76 amass: I r 3 acentrally disposed circular bevelled male portion I2 which strikes thecentral portion of the head, as shown in Fig. 15, which causes thecentral portion of the side walls of the slot to assume 5 a dovetailedposition. The die may be bevelled as shown or it may be flat, or evenmay have a plurality of protruding portions which engage the centralportion of the head on either sidh of the slot. v

Likewise, in Fig. 17 the die I5 is adapted to receive the screw 16provided with a round or button head 11 which is formed with aconventional transverse slot II. The punch I9.is formed with a circularconcave portion 80 of substantially the contour shown, the essential'thing being that the main force of the blow be exerted on'the centralportion of the head.

In Fig. 19 a flat headed screw 82 having an arcuate dovetailed slot 83inaccordance with 20 the hereindescribed method and having an uppersurface similar to that shown in Fig. 5, is shown mounted on a bitportion 84 of a screw driver of the type disclosed in my aforesaidcopending application. The upper surface of the head is engaged by asleeve 85 carried by the bit, which sleeve is in either positive oryieldable engagement with the head. The bit may be operatively connectedwith the handle (not shown) of the driver and the sleeve carried therebyand longitu- 8 dinally movable thereon, or the sleeve may be secured tothe handle and the bit portion carried in a transverse slot in the endof the sleeve. In the latter instance the bit is caused to revolve bythe sleeve. 35 What I claim is: I

' 1. The method otforminga screw head which consists in supporting ablank in a die, striking the head portion with a combined heading andslot forming punch and then striking thecentral 40 portion of theformed, slotted head with'an upsetting punch to cause the upper centralportions of the side walls of the slot to converge inwardly.

2. The method of forming a screw head of the class described whichconsists in supporting a blank in a die, upsetting the head portion ofthe 5 blank with a combined heading and slot forming punch, thenupsetting the formed head with a punch which engages the head adjacentto the central portion of the slot to cause the upper central edges ofthe said slot to converge inwardly.

3. The method of forming .a screw head which consists of supporting ablank .in a die, the head portion of the blank protruding beyond the endof thedie, striking the protruding portion with a heading punch providedwith a male portion 15 for striking a transverse slot in the head, thenstriking the slotted head with a punch adapted to somewhat flatten thehead and cause. the central portion of the side walls of the slot toconverge inwardly to form a centrally disposed dovetail portion.

4. The method of forming a screw head which consists in upsetting thehead to provide a curve of less radius on the upper surface than isdesired in the finished screw, striking a transverse slot 25 in the headand then striking the upper surface with a die or such contour as toflatten same and cause the upper central portions of the sidewalls toconverge inwardly.

5. The method of forming a screw head which consists in the steps ofsupporting a screw blank in a die, striking the head portion with a dieI adapted to partially form the head, then striking the upper surface ofthe partially formed head with a combined head and slot forming punch,and then striking the central portion of the upper surface of theslotted head with an upsetting punch to-cause the upper central portionof the side walls to converge inwardly.

THEODOR A. O'LEARY.

